Is the enemy of my enemy my friend? That's the question when it comes to the U.S. and Iran right now. Both countries have strategic interests in containing ISIS, the Islamic State. But cooperation between the two nations could be difficult, not just for historical reasons, but because of ongoing negotiations over Iran's nuclear program. The U.S. imposed more sanctions on Iranian businesses, banks and individuals on Friday. Iran said that will have a negative effect on nuclear negotiations. Karim Sadjadpour is a senior associate at the Carnegie Endowment for International Peace and a leading researcher on Iran. He's here in our studio. Welcome.

KARIM SADJADPOUR: Thank you, Linda.

WERTHEIMER: So since the 1979 Iranian revolution, U.S. presidents have tried several times to cooperate with Iran against common enemies. Do you think that might work this time fighting the Islamic State?

SADJADPOUR: Well, Linda, as you said, since 1979 the U.S. and Iran have had numerous common enemies. There was the USSR. There was Saddam Hussein, the Taliban in Afghanistan. And at times there has been tactical cooperation between the United States and Iran - in particular in helping to remove the Taliban from Afghanistan. But it's never turned into a strategic cooperation and a type of cooperation that would lead to a rapprochement. So I expect in the case of ISIS, or the Islamic State, we may see U.S.-Iran tactical cooperation. But it's not going to build into something that would lead to a political rapprochement.

WERTHEIMER: So do you think that there is still - you do think there is still room to sort of work with Iran even though it's been on the opposite side from the U.S. on all kinds of policy questions?

SADJADPOUR: Well, both the U.S. and Iran, as you mentioned, have a major interest in curtailing the rise of these radical Sunni groups like ISIS. The challenge in our dealings with Iran is the moderate officials who are keen on working with America against radical Sunni groups like ISIS and those more hard-line officials in Tehran who, in the past, have been willing to work with radical Sunni groups against America. And the challenge we have in our dealings with the Iranian government are those moderate Iranian officials who talk to America haven't really been able to deliver. And the hard-line officials who can deliver don't talk to America.

WERTHEIMER: Well, we've seen something interesting happening this weekend. The Iranian President, Hassan Rouhani, seemed to take a step back returning to the position that the U.S. cannot be trusted. But how does that play with the much more conciliatory tone we've been hearing from this foreign minister who's currently traveling around Europe calling on his counterparts?

SADJADPOUR: Well, I would say both Hassan Rouhani and his foreign minister, Javad Zarif, have an interest in seeing a more conciliatory relationship between America and Iran. And Rouhani, in particular, has invested all of his political capital in reaching a nuclear deal with the United States. The sanctions that were passed against Iran over the last couple days puts Rouhani in a very difficult position. So he lashed out against the United States. But I think the foreign minister - Iran's foreign minister - recognizes that if they're not able to reach a nuclear deal with the United States, they will be rendered lame ducks very quickly. So despite their anger with the United States for this recent round of sanctions, they have - they're heavily invested in trying to reach this nuclear deal.

WERTHEIMER: Do you think ISIS - the pressure on both sides from ISIS - means they're more likely or less likely to get to that deal?

SADJADPOUR: You know, that's a very good question. You could make the argument that, at the moment, Iran feels more vulnerable because they have these radical Sunni jihadists on their border. And they're hence more likely to reach a nuclear deal. But you could also make the opposite argument that Iran senses that America is more vulnerable now because of these radical Sunni groups. And America needs Iran's help in fighting ISIS. Therefore Iran can be more intransigent on the nuclear issue. My suspicion is the latter - that Iranian officials, at the moment, feel emboldened. And they feel America needs their help more than they do.

WERTHEIMER: Karim Sadjadpour - he is the senior associate at the Carnegie Endowment for International Peace. Thank you very much for coming in.

SADJADPOUR: Any time, Linda. Transcript provided by NPR, Copyright NPR.